One of the greatest benefits of an open plan office is that people share information without the need to have meetings. Overhearing telephone conversations and impromptu discussions are great examples of "constructive eavesdropping" that can help the organization move forward.
On the other hand, an open plan office deprives you of any sort of privacy - and can be very distracting.
This morning's Globe and Mail has a great article about the new face of work environments. I provide a number of concrete suggestions on how to get the benefits - and mitigate the negatives. The article is also available on Workopolis.